Power lawn mower with air filtering screen



Sept. 13, 1949. H. H. PACKWOOD POWER LAWN MOWER WITH AIR FILTERINGSCREEN Original Filed Aug. 7, I946 R O T N E v m 6" 44M ATTORNEY 71620H. Fae/(wood ssamdse uaim UNITED STATES PATENT orrica PQWEB LAWN MOWERWITH AIR FILTEBING SCREEN 'Heaa H. Packwood, Baton Rouge, La. Original N2,445,965, dated July 27, 1948, Serial No. 688,940, August 7, 1946.Application for reissue September 2, 1948, Serb! No. 47,521

- is to provide a motor having a rotary cooling fan with novel means forpreventing light' weight particles such as leaf and paper fragments frombeing drawn into the cooling fan housing by the air stream passingthrough the housing.

A primary object of the invention is to provide a lawnmower motor withimproved air cooling means characterized by means provided to preventlight weight particles from being carried into the motor coolingpassages. Extensive and increasing use is now'being made'of small lawnmowers propelled by hand, but in which a small, air cooled motor ismounted on the lawn mower framework and is operatively connected to, androtatesacross the cutting element of the lawn mower. In the use of suchlawn mowers, trouble is caused by the clogging of the cooling airpassages in the motor structure by severed grass blades, leaf and paperfragments, and other small bodies drawn into the fan housing through itsair inlet by the air moved into the fan housing and thence into themotor cooling passages. The mm tor usually mounted on a hand-propelledlawn mower is a small internal combustion engine provided withside-by-side external, deep, heat dissipating ribs or fins, separated byrelatively deep and narrow grooves which serve as passages for thecooling air. Light bodies swept into said grooves by the cooling airtend to lodge in, and choke the grooves, particularly as freshly severedgrass blade tips and other moist bodies lodging in the grooves tend torapidly dry out and firmly adhere to the walls of the groove.

In accordance with the present invention, I mount a screen on the fanimpeller to rotate with the latter and to extend across the path of airflow into the fan housing through its air inlet, and so arrange theimpeller and screen that the latter is outside of the fan housing. Inconsequence, many of the particles arrested by the rotating screen aredislodged b the action of forces created by the operation of the lawnmower, and those not so dislodged, may be readily scraped or knocked oilthe rotating screen, and remain outside of the fan housing. I thus avoidobjections to the use of screen arrangements for fans previouslyproposed. In most arrangements previously proposed, a screen has beenattached to the outer side of the fan housing at the margin of the airinlet. Such a stationary screen is open to the practical objection thatlight particles which are arrested by the screen, adhere thereto and 2tend to accumulate on the screen and impair the movement of air into thetan. In another old proposed arrangement, a screen is mounted on an airimpeller within a fan housing, at the inlet side of the air inlet.Particles arrested by such a screen and not dislodged by the operationof the mower, are not readily removed from the screen, and, whendislodged, remain in the fan housing.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to, and forming apart of this specification. For a better understanding of the invention,however, its advantages and specific objects attained by its use,reference should be had to the accompanying drawlugs and descriptivematter in which I have illustrated and described preferred embodimentsoi the invention.

Of the drawings:

Fig. 1 is a perspective view of a lawn mower;

Fig. 2 is a perspective view of the motor and cooling fan of the lawnmower shown in Fig. 1;

Fig. 3 is an elevation partly in section on the line 3-3 of Fig. 2; and

Fig. 4 is a sectional elevation illustrating a modified construction.

In the drawings I have illustrated the use or the present invention byway of example, in a lawn mower of the general type and form disclosedin my prior Patent No. 2,287,126 of June 23, 1942. As shown in Fig. 1,the lawn mower comprises a frame-work A supported by rear groundengaging wheels B and by a front roller C. The rotating cutter element Dof the lawn mower is supported for rotation about a vertical axis solocated that the horizontal cutting blades d at the opposite ends of theelement D move along an annular path which surrounds the roller 0'. Thebody portion of the element D comprises inclined or are shaped portionsD, connected at their lower ends to the cutting blade wheel :1 and acentral horizontal portion to which a driving pulley E is attached. Thecutter element is rotated by a belt e looped about the pulley E andabout a driving pulley h carried by the horizontal shaft h of aninternal combustion engine H mounted on the lawn mower framework withthe shaft h extending transversely to the plane including the axis ofthe pulley E and intersecting the pulley h.

As shown, the motor H comprises a single, vertically disposed,combustion chamber or cylinder H. The latter is provided with a seriesof external heat dissipating ribs or fins H in the form of rings coaxialwith the chamber H, and of a radial extent substantially greater thanthe distance be- 3 tween the adjacent fins. Usually and as shown, thewidth of the space between adjacent ribs H increases from the inner edgeto the outer edge of the space, at which the width is of the order ofthree-eighths of an inch or less. as shown, the upper end of the chamberor cylinder H is provided with uprising ribs or has H arrangedside-by-side and substantially parallel with the shaft h, and separatedby narrow spaces or grooves.

when the lawn mower is in operation, cooling 7 air is moved along thesurface of the fins or ribs H and B by fan means shown as ofconventional type comprising a rotary impeller I, and a fan casing orhousing i having a lateral air inlet i substantially coaxial with theengine shaft 7:. As shown, the impeller I comprises a heavy disk-likebody portion I mounted on the engine shaft h and serving as the engineflywheel. The side of the body I adiacent the lateral inlet 1' isconvex, and integral fan blades or vanes I project from the peripheralportion of the convex side of the body I. The vanes F extend away fromthe impeller body in the axial direction of the fan. and, as shown, theysurround and extend radially away from an air space between the body Iand inlet 1. The fan housing is formed with an upper outlet portionhaving a side opening P alongside the engine so as to discharge air intothe grooves between the ribs or fins H and H The fan housing is alsoformed with a bailie 1 extending over the impeller vanes at one side ofthe vertical plane through the impeller axis so as to prevent downwardair slip movement at the side of the fan housing in which the vanes movedownward.

In accordance with the present invention, means are provided for theattachment to the impeller I of a screen J of relatively coarse meshexternal to the fan housing and extending across the path of air flowinto the fan chamber through its inlet i. As shown in Figs. 2 and 3, thescreen is of flat annular form and surrounds the hub or body portion ofthe engine starting pulley K carried by the engine shaft )2. and aroundwhich a rope or cord may be wound for use in spinning the shaft in tostart the engine in a manner in which small internal combustion enginesare customarily started. The central opening in the screen is shown asreceiving the starting pulley K and is not needed when the invention isused with an engine in which the starting pulley is omitted. In suchcase, the central portion of the screen may be made of the same pervlousmaterial as the rest of the fan or it may be made of imperviousmaterial, such for example as a disk of sheet meta1.-

In the arrangement shown in Figs. 2 and 3, the screen J is attached atits periphery to an annular member J having a cylindrical portionextendin through the air inlet 1. The member J is connected to andsupported by the outer ends of spider arms J which have their inner endsatached to the impeller body 1'. Other arrange ments for attaching thescreen to the impeller may be employed, and in a preferred arrangementshown in Fig. 4, the screen is attached to the starting pulley member K.In the particular construction shown in Fig. 4, the screen is formedwith a cylindrical flange portion J which surrounds, and fits snugly onand is spot welded to the hub portion of the startingpulley K.Alternatively, the body portion of the screen may be welded or otherwisesecured to the adjacent pulley groove wall K. The screen J shown in Fig.4 is a. woven wire one-quarter inch mesh screen made of relatively heavywire and reinforced at its periphery by a metal ring J welded to theside of the screen. The screen diameter is a half inch or more greaterthan the diameter of the inlet opening i and a clearance space, whichmay be about one-sixteenth of an inch thick, is provided between theperipheral portion of the screen and the portion of the fan casing whichit overlaps.

Ordinarily, the screen J may be flat as shown, though the screen mayalso be convex or cylindrical in form. The screen may be formed ofperforated .sheet metal or other usual screen forming material, but Ihave found it advantageous to employ a screen of woven wire ofrelatively large diameter, as the surface roughness of such a screenseems to facilitate the dislodgment of grass blades, pieces of paper,etc. arrested by the screen.

with the screen outside of the fan casing as shown, particles arrestedby the screen and dislodged are free to move laterally away from thescreen and out of the path of air flow into the fan housing. Thedislodgment of the particles may be effected in various ways, butordinarily is effected by one at least, and usually by more than one ofthe following forces of actions, namely, the force of gravity,centrifugal force, vibrations due to the operation of the mower, the outflow, adjacent the periphery of the inlet opening i. of

some of the air drawn intothe central portion of the space surrounded bythe fan blades, and

manual scrapping and jarring actions. The clogging of the engine coolingair channels is not the only disadvantage avoided by the use of thepresent invention. In some cases grass blades or other solid particlesif allowed to enter the fan structure create trouble therein. Thus, for

example, some internal combustion engines are provided with an enginegovernor comprising a vane adjacent the path of the tips of the fanrunes and arranged to move in response to variations in the force of theimpact of the air passing away from the vanes. Grass blades and the likedrawn into the fan housing of such an engine'may seriously interferewith the operation of its governor.

While the invention is of especial utility for lawn mower use it isadapted for other uses. In accordance with the provisions of thestatutes, I have illustrated and described the best forms of embodimentof my invention now known to me, but it will be apparent to thoseskilled in the art that changes may be made in the forms of theapparatus disclosed without departing from the sipirt of my invention asset forth in the appended claims, and that in some cases certainfeatures of my invention may be used to advantage without acorresponding use of other features.

Having now described my invention, what I claim as new and desired tosecure by Letters Patent, is:

1. In a lawn mower, the combination with the lawn mower framework, of arotary grass cutter and a motor having a rotating driving shaft mountedin said frame work, a motor cooling fan comprising a rotating airimpeller carried by said shaft at one side of said motor and a fancasing enclosing said impeller and having an air inlet at the oppositeside of the impeller from said motor and having an outlet for thedischarge of cooling air against the motor. and an inlet screen carriedby said shaft at the outer side of said inlet opening and extendingacross the path of air ilow through said opening, whereby bodies whichthe air drawn into the casing through said inlet tends to carry into thefan casing, are arrested by the screen and when dislodged, pass into thespace external to said casing.

2. In a lawn mower, the combination with the lawn mower framework, of arotary grass cutter and an internal combustion motor having a rotatingdriving shaft mounted in said framework, a motor cooling fan comprisinga rotating air impeller carried by said shaft at one side of the motorand a fan casing enclosing said impeller and having an air inlet at theopposite side of the impeller from said motor and having an outlet forthe discharge of cooling air against the motor, a starting pulleymounted on said shaft and having a portion at the outer side of saidinlet opening, and an inlet screen at the outer side of said inletopening and extending across the path of air flow through said openingand connected to and supported and rotated by said pulley, wherebybodies which the air drawn into the casing through said inlet tends tocarry into the fan casing, are arrested by the screen and whendislodged, pass into the space external to said casing.

3. For use in a lawn mower, a motor having a rotating driving shaft, 8.motor cooling fan com prising a rotating air impeller carried by saidshaft at one side of said motor and a fan casing enclosing said impellerand having an air inlet at the opposite side of the impeller from saidmotor and having an outlet for the discharge of cooling air against themotor, and an inlet screen carried by said shaft at the outer side ofsaid inlet opening and at least substantially coextensive with saidopening and extending across the path of air flow through said opening,whereby bodies which the air drawn into the casing through said inlettends to carry into the fan casing, are arrested by the screen and whendislodged, pass into the space external to said casing.

4. For use in a lawn mower, a motor having a rotating driving shaft, amotor cooling fan comprising a rotating air impeller carried by saidshaft at one side of the motor and a fan casing enclosing said impellerand having an air inlet at the opposite side of the impeller from saidmotor and having an outlet for the discharge of cooling air against themotor, a starting pulley mounted on said shaft and having a portion atthe outer side of said inlet opening and at least substantiallycoextensive with said opening, and an inlet screen at the other side ofsaid inlet opening and extending across the path of air flow throughsaid opening and connected to and supported and rotated by said pulley,whereby bodies which the air drawn into the casing through said inlettends to carry into the fan casing, are arrested by the screen and whendislodged, pass into the space external to said casing,

5. A driving mechanism as specified in claim 4, in which said inletscreen has a peripheral portion overlapping the portion of the fancasing adjacent and surrounding the fan inlet.

HEZA H. PACKWOOD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 579,081 Rembert Mar. 16, 1897585,188 Davis June 29, 1897 1,037,659 Rembert Sept. 3, 1912 1,631,549Pease June 7, 1927 1,638,067 Szekely Aug. 9, 1927 1,649,220 Goodloe Nov.15 ,1927 1,762,028 Phelps June 3, 1930 1,789,871 Knight Jan. 20, 1.9312,167,786 Taylor Aug. 1, 1939 2,172,992 Stegeman Sept. 12, 19392,244,165 MacFarland et al. June 3, 1941 2,346,148 Bosma Apr. 11, 1944

